XMonad.Prelude: add the WindowScreen type

`WindowScreen` is a type synonym for the specialized `Screen` type, that
results from the `WindowSet` definition in XMonad.Core. Having this type
defined and exported in a central module saves extension developers from
trying to reconstruct it, whenever the general `Screen i l a sid sd` is
not suitable.

Note: this should be moved to `XMonad.Core` in the next core release.

CHANGES.md

@@ -121,6 +121,9 @@
     - Added `keymaskToString` and `keyToString` to show a key mask and a
       key in the style of `XMonad.Util.EZConfig`.
 
+    - Added `WindowScreen`, which is a type synonym for the specialized `Screen`
+      type, that results from the `WindowSet` definition in `XMonad.Core`.
+
   * `XMonad.Util.XUtils`
 
     - Added `withSimpleWindow`, `showSimpleWindow`, `WindowConfig`, and

XMonad/Actions/EasyMotion.hs

@@ -271,7 +271,7 @@ handleSelectWindow c = do
         $ M.elems
         $ M.mapWithKey (\sid ks -> buildOverlays ks <$> sortedOverlayWindows sid) m
      where
-      screenById :: ScreenId -> Maybe (W.Screen WorkspaceId (Layout Window) Window ScreenId ScreenDetail)
+      screenById :: ScreenId -> Maybe WindowScreen
       screenById sid = find ((== sid) . W.screen) (W.screens ws)
       visibleWindowsOnScreen :: ScreenId -> [Window]
       visibleWindowsOnScreen sid = filter (`elem` toList mappedWins) $ W.integrate' $ screenById sid >>= W.stack . W.workspace

XMonad/Actions/Navigation2D.hs

@@ -388,7 +388,7 @@ data Navigation2DConfig = Navigation2DConfig
   }
 
 -- | Shorthand for the tedious screen type
-type Screen = W.Screen WorkspaceId (Layout Window) Window ScreenId ScreenDetail
+type Screen = WindowScreen
 
 -- | Convenience function for enabling Navigation2D with typical keybindings.
 -- Takes a Navigation2DConfig, an (up, left, down, right) tuple, a mapping from

XMonad/Layout/IndependentScreens.hs

@@ -148,7 +148,7 @@ withWspOnScreen screenId operation ws = case workspaceOnScreen screenId ws of
     Nothing -> ws
 
 -- | Get the workspace that is active on a given screen.
-screenOnMonitor :: ScreenId -> WindowSet -> Maybe (W.Screen WorkspaceId (Layout Window) Window ScreenId ScreenDetail)
+screenOnMonitor :: ScreenId -> WindowSet -> Maybe WindowScreen
 screenOnMonitor screenId ws = find ((screenId ==) . W.screen) (W.current ws : W.visible ws)
 
 -- | Focus a window, switching workspace on the correct Xinerama screen if neccessary.

XMonad/Prelude.hs

@@ -32,6 +32,7 @@ module XMonad.Prelude (
     specialKeys,
     multimediaKeys,
     functionKeys,
+    WindowScreen,
 ) where
 
 import Foreign (alloca, peek)
@@ -57,6 +58,7 @@ import Data.Bits
 import Data.List.NonEmpty (NonEmpty ((:|)))
 import Data.Tuple (swap)
 import GHC.Stack
+import qualified XMonad.StackSet as W
 
 -- | Short for 'fromIntegral'.
 fi :: (Integral a, Num b) => a -> b
@@ -415,3 +417,7 @@ multimediaKeys = filter ((/= noSymbol) . snd) . map (id &&& stringToKeysym) $
   , "XF86_Prev_VMode"
   , "XF86Bluetooth"
   ]
+
+-- | The specialized 'W.Screen' derived from 'WindowSet'.
+type WindowScreen -- FIXME move to core
+    = W.Screen WorkspaceId (Layout Window) Window ScreenId ScreenDetail

XMonad/Util/Loggers.hs

@@ -48,7 +48,7 @@ module XMonad.Util.Loggers (
 
   ) where
 
-import XMonad (liftIO, Window, gets)
+import XMonad (liftIO, gets)
 import XMonad.Core
 import qualified XMonad.StackSet as W
 import XMonad.Hooks.StatusBar.PP
@@ -56,7 +56,7 @@ import XMonad.Util.Font (Align (..))
 import XMonad.Util.NamedWindows (getName)
 
 import Control.Exception as E
-import XMonad.Prelude (find, fromMaybe, isPrefixOf, isSuffixOf)
+import XMonad.Prelude (find, fromMaybe, isPrefixOf, isSuffixOf, WindowScreen)
 import Data.Time (defaultTimeLocale, formatTime, getCurrentTime)
 import System.Directory (getDirectoryContents)
 import System.IO (hGetLine)
@@ -272,9 +272,6 @@ logLayoutOnScreen :: ScreenId -> Logger
 logLayoutOnScreen =
   withScreen $ logConst . description . W.layout . W.workspace
 
--- | A shortcut to a screen
-type WindowScreen = W.Screen WorkspaceId (Layout Window) Window ScreenId ScreenDetail
-
 -- | A helper function to create screen-specific loggers.
 withScreen :: (WindowScreen -> Logger) -> ScreenId -> Logger
 withScreen f n = do

XMonad/Util/PureX.hs

@@ -53,7 +53,7 @@ module XMonad.Util.PureX (
 
 -- xmonad
 import XMonad
-import XMonad.Prelude (Any (..), liftA2)
+import XMonad.Prelude (Any (..), liftA2, WindowScreen)
 import qualified XMonad.StackSet as W
 import qualified XMonad.Actions.FocusNth
 
@@ -220,9 +220,7 @@ peek :: XLike m => m (Maybe Window)
 peek = withWindowSet' (return . W.peek)
 
 -- | Get the current screen.
-curScreen
+curScreen :: XLike m => m WindowScreen
-  :: XLike m
-  => m (W.Screen WorkspaceId (Layout Window) Window ScreenId ScreenDetail)
 curScreen = withWindowSet' (return . W.current)
 
 -- | Get the current workspace.